1. Field of the Invention
The invention relates to a winding device for winding a material web into a roll. The winding device includes a roll carrier which includes at least two driven roll support members which are each movable between a winding position and an exchange position. The winding device further includes a transfer device and a contact pressure device.
2. Description of the Related Art
In the following, the invention will be described in connection with winding of foils. This is the principal field of application. However, other material webs can also be wound into rolls in the same manner.
As a rule, material webs must after the end of a manufacturing process be wound into rolls which can be manipulated. Such material web rolls are also sometimes used for the intermediate storage of the material web. However, the capacity of such material web rolls is limited, i.e., an exchange of the roll is required when a predetermined length of the material web has been wound up. Such an exchange of rolls requires an interruption in the feeding of the material web. In that case, there is sufficient time for severing the material web, for securing the end of the finished wound-up roll, and for fastening the beginning to another new roll core. However, this type of procedure is not possible in practice if the material web is supplied continuously. This is the case, for example, in the manufacture of foils which are extruded. In that case, the material web must be severed practically instantly and the beginning of the material web must be secured on a new roll core, so that winding can take place without interruption.
The transfer of the material web from a finished material web roll to a roll core is known in the art. There are several possibilities. In more complicated arrangements, the material web is severed simultaneously over the entire width, so that a cut is formed which extends essentially perpendicularly over the web travel direction. At the same time as the web is severed, the beginning of the material web formed during the performance of the cut is conducted around the new winding sleeve and, possibly after traveling through a nip, is conducted underneath the material web which continues to be supplied, so that the material web holds itself on the roll core. In this case, it is not necessary to prepare the roll core, for example, by rendering it adhesive. In many cases, such a preparation is not even desirable because the object is to save costs. In simple transfer devices, a cutting knife is moved transversely of the material web. Since the material web continues to travel, essentially an oblique cut is produced. The tip created in one side of the material web as a result of the cut can then be utilized for fastening the tip to the new winding sleeve. However, this type of procedure has the result that the material web is not wound up uniformly. Rather, a helically shaped step location may be produced which later may lead to undesirable problems.
An additional difficulty is the fact that some material webs are supposed to be wound in such a way that their upper sides are located on the outer side of the wound-up roll. On the other hand, other material webs have to be wound in such a way that their upper sides face inwardly. The automatic exchange of the winding directions has practically not been possible in the past even with a relatively complicated arrangement. It is not sufficient to simply reverse the drive of the roll because the conditions in which the material web is wound onto the roll are no longer correct.
Therefore, it is the primary object of the present invention to provide a winding device which can be operated independently of the winding direction with an essentially equally high winding quality.
In accordance with the present invention, a winding device of the above-described type is proposed in which the roll support members can be driven in two different directions of rotation. A first material web path at the end of which the material web travels in a first direction onto the roll and a second material web path at the end of which the material web travels in a second direction onto the roll, are proposed. The transfer device includes a first cutting device which can be moved from a first side into the material web and a second cutting device which can be moved from a second side into the material web.
In the winding device according to the present invention, a change of the winding direction can be achieved in a relatively simple manner. The material web must only be diverted from one material web path to the other material web path. By changing the web travel direction in the winding device, the material web is conducted in such a way that it travels in the correct direction onto the roll. This correct direction is usually practically tangential.
The roll drive can also be combined with an appropriate control which controls the roll drive in dependence on the material web pattern into the correct direction. Alternatively, it may also be provided that a material web path is only released if the roll drive takes place in the correct direction. Finally, two cutting devices are provided which are movable into the material web from two different sides for cutting the material web. This ensures independently of the winding direction that the material web can always be conducted around the new winding sleeve by means of the cutting device, so that the transfer can also take place almost independently of the winding direction with the desired high quality, i.e., practically without wrinkles from the first winding layer. By adjusting operational elements, it is possible at both transfer devices to adapt to different winding sleeve diameters within a relatively wide range.
In accordance with a preferred embodiment, the two cutting devices are constructed in a mirror-symmetrical configuration relative to each other. An exact symmetry is not required. Smaller deviations which may be due to structural causes are readily permissible. If the two cutting devices are arranged essentially in a mirror-symmetrical configuration, then cutting by the two cutting devices takes place in the same manner and the material web is guided in the same manner onto the new winding sleeve independently of which cutting device is active. Consequently, the quality of the first winding layers is the same for both winding directions. It is already ensured at the beginning of the winding process that the rolls are begun practically equally in both winding directions.
Each cutting device preferably has a pressure member on the opposite side of the material web. The pressure members are also constructed and arranged in a mirror-symmetrical configuration relative to each other and are adjustable to different sleeve diameters. Such a pressure member facilitates the cutting of the material web. The pressure member essentially forms a beam at which the material web can be sheared of f by the cutting device. This is also true if the cutting device and the pressure member are not constructed with cutting edges which contact each other, as is the case in a shear. When the pressure member is moved towards the material web, the pressure member prevents the material web from yielding too much and to later produce wrinkles on the winding sleeve and, thus, acts as a counter pressure member. In other words, the pressure member produces a tension in the material web which is sufficient for severing the material web with a sudden cut and to prevent contact wrinkles at the beginning of the winding process.
In accordance with a preferred embodiment, the pressure member of a cutting device is arranged on a carriage which is displaceable relative to a knife unit of the other cutting device. If it is desired to use two cutting devices, there is the problem with respect to the pressure member that only a limited amount of space is available. If the pressure member of one cutting device is displaceable, then it is possible to move this pressure member out of the range of action of the other cutting device if this cutting device is to be operated. Consequently, the necessary space of movement for the cutting device is provided in a simple manner without sacrificing the function of the pressure members for both winding directions.
In accordance with a particularly preferred feature, the pressure member includes a lever arm which is pivotably mounted on the carriage. This provides a larger free space for the displaceability of the carriage. If the carriage is to be moved, the pressure member can be pivoted in such a way that it does not collide with any additional structural components. The movement control becomes relatively simple as a result.
In accordance with another particularly preferred feature, an auxiliary arm is arranged on the lever arm, wherein the auxiliary arm can be pivoted in a controlled manner relative to the lever arm and wherein the auxiliary arm has a cutting edge. Consequently, the auxiliary arm forms the actual operational element which is used for cutting the material web. As already mentioned, it is not absolutely required that the cutting edge interacts with the cutting device in the manner of a shear. It is sufficient if the cutting edge tensions the material web sufficiently for enabling the cutting device to carry out an impact cut.
In accordance with another preferred feature, the auxiliary arm can be positioned in a position in which it is tangential relative to a winding sleeve onto which the material web is to be transferred. Consequently, when the cut is carried out, the free length of the material web which travels into the cutting device is very short.
Each cutting device advantageously acts simultaneously along the entire width of the material web. This produces a cut which extends essentially at a right angle relative to the travel direction. Consequently, the subsequently wound material web is uniformly wound over the entire width.
The contact pressure device preferably includes a pressure carriage which is displaceable relative to the roll carrier, wherein the carriages supporting the cutting devices are displaceable relative to the pressure carriage. A displaceable pressure carriage ensures that the diameter of the roll can increase without having to move the roll support members. The pressure carriage ensures that the contact pressure roller always can rest against the roll with the necessary pressure for achieving a predetermined pattern of the winding hardness. The cutting devices, on the other hand, are displaceable relative to the pressure carriage so that they are out of the way during winding.
Each cutting device preferably includes a guide roller which can be moved into the material web, wherein the guide roller is arranged on a carrier and a knife can be pivoted relative to the carrier. The material web which still travels onto the full roll can be guided by means of the guide roller around the empty winding sleeve, so that the remaining length which must still be guided by the knife around the winding sleeve can be kept small.
In accordance with another preferred feature, each pressure member is provided with a deflection roller whichxe2x80x94with the intermediate arrangement of the material webxe2x80x94can be placed behind the cut against the new winding roller and forms a take-up nip. When the knives have cut the material web, the beginning of the material web formed by the cut is conducted practically immediately after the cut into the nip between the winding sleeve and the deflection roller and is secured at this location by the subsequently supplied material web. The material web is then held on the winding sleeve by its own tension after a few rotations, so that no additional holding means are required. Accordingly, it is then no longer required to prepare the winding sleeve, i.e., by rendering it adhesive.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.